Oligodendroglia can be isolated in bulk from fresh lamb or bovine brain subcortical white matter or from human autopsy tissue. The purified homogeneous preparation of cells can be maintained as suspension cultures where they remain intact and viable. The cells are metabolically very active and synthesize a variety of lipids and proteins, especially those found enriched in myelin. While in culture the cells elaborate whorls of membrane adjacent to the cell surface. After purification and analysis of these membrane whorls, it was found they have properties in common with mature compacted myelin, although there are also distinct differences. Possibly these membrane whorls are an early form of myelin. To study the proteins found in the oligodendroglial plasma membranes, many techniques will be used. These include surface labeling probes, lectin binding, and immunoprecipitation methods. Thus protein common to brain and unique to oligodendroglia will be identified. The findings from these investigations will then be applied to human conditions of demyelination to study the events occurring during the disease process at a molecular level.